Synthetic resins such as polymethyl methacrylate resin, polycarbonate resin, polystyrene resin, cyclic polyolefin resin, polyethylene terephthalate resin, and triacetyl cellulose resin have advantageous properties including light weight, high transparency, and high workability, and therefore, these synthetic resins are recently finding wide applications in the field of optical disks such as CD and DVD, display windows such as liquid crystal and EL panels, and various functional films.
When such products are used, various types of smudges and fingerprints deposit on the surface of such resin, and since such smudge and fingerprint deposition is not preferable, the surface of an optical information medium is often subjected to an adequate surface treatment to thereby improve the smudge proof property, reduce fingerprint deposition, and improve removal of the fingerprints. For example, attempts have been made to provide a variety of water and oil repellent treatments on the surface of an optical information medium.
In order to improve scratch resistance of such surface, a transparent scratch resistant hard coating was commonly formed on the surface of the medium on the side of the incidence of the write and/or read beam. Such hard coating has been formed by coating a siloxane compound having a basket structure produced by hydrolyzing and condensing a compound having two or more photoreactive groups such as (meth)acryloyl group in one molecule or an alkoxysilane having a photoreactive group such as (meth)acryloyl group in the presence of a basic catalyst (JP-A 2002-363414 and JP-A 2004-143449: Patent Documents 1 and 2), or by coating a composition containing a reaction product of an alkoxysilane having a photoreactive group and a colloidal silica on the surface of the medium, and then curing the coating by irradiation of an active energy beam such as UV. This type of hard coating which has been formed principally for the purpose of improving the scratch resistance, however, had been inferior in the crack resistance, and smudge proof property for smudges such as fingerprints and removability of oil-base felted markers by wiping could not have been expected from such coating.
In view of such situation, a siloxane compound having a basket structure produced by hydrolyzing and condensing an alkoxysilane having a polymerizable functional group and an alkoxysilane having a perfluoroalkyl group in the presence of a basic catalyst was proposed (JP-B 3603133 and JP-B 3572989: Patent Documents 3 and 4). A coating formed by curing a composition containing such compound exhibits a larger contact angle with oleic acid indicating an improvement in the smudge proof property. However, removability of the oil-base felted marker by wiping was still insufficient, and this coating exhibited a drastic loss of the abrasion resistance.
In order to improve antistatic property, addition of various antistatic agents have also been attempted. Despite proposals of adding of a reaction product of polyether-modified silicone and lithium perchlorate (JP-A 5-320626: Patent Document 5), adding of a reaction product of polyfunctional acryl and lithium perchlorate (JP-B 3673590: Patent Document 6), and adding of a mixture of polyfunctional acrylate and (CF3SO2)2NLi (JP-A 9-278831 and JP-A 2001-288325: Patent Documents 7 and 8), the coating produced in these attempts had insufficient scratch resistance.
In view of such situation, addition of a mixture of a silane hydrolysate and (CF3SO2)2NLi (JP-A 2005-146110 and JP-A 2006-70120: Patent Documents 9 and 10) was proposed in order to improve the scratch resistance. The coating produced in these attempts, however, had insufficient smudge proof properties including the resistance to oil-base felted markers.